consider a relation s over the attributes a and b

Question

Consider a relation s over the attributes A and B with the following characteristics:

• 5,000 tuples with 10 tuples per page
• A 2-level B+ tree index on attribute A with up to 100 index entries per page
• Attribute A is a candidate key of s
• The values that the attribute A takes in relation s are uniformly distributed in the range 1to 100,000.

(a)    Assuming that the aforesaid index on A is unclustered, estimate the number of disk accesses needed to compute the range query σ_{A>1000 ^ A<6000} (s).

(b)   What would be the cost if the above index were clustered? Explain your reasoning.